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TypeScript

TypeScript Best Practices for High-Quality and Flexible Coding

Last Updated on January 2, 2025

Quick Summary

This blog covers essential TypeScript best practices to enhance code quality, maintenance, and flexibility. The tips will help you to improve development efficiency, reduce bugs, and make code more reliable and scalable.Whether you are a beginner or an experienced developer, this comprehensive guide of best Typescript best practices will upscale your coding.

Introduction

Spending hours, even days, and months on projects and seeing them crash due to tiny or seemingly insignificant errors could be frustrating and time-consuming. Not only does it make your hard work futile, but it instantly derails the entire process. However, there’s a solution for it: TypeScript.

According to the StackOverflow Survey 2023, 38.87% of developers use TypeScript, ranking it among the top three languages. This widespread adoption is a testament to its power to catch errors early and ensure code reliability.
Moreover, the applications become more complex, and the need for clear, flexible, and high-quality code is more essential. Adopting TypeScript best practices 2024 improves readability, reduces errors, and boost collaboration among team members.
This blog discusses TypeScript best practices, helping you write clean, robust, and maintainable code to streamline development workflow.

Core TypeScript Best Practices

1. Start with Strict Type-Checking

Type-checking is a crucial TypeScript best practice every expert should follow for a safe code environment. This will ensure the code is relevant and robust and assist in identifying errors during early development.

By activating strict mode in your tsconfig.json file, TypeScript will execute at a higher safety level and enhance code reliability. Strict mode allows you to provide reliable code typing, improve overall code quality, and prevent common mistakes like undefined values and null.

Essential Tips:

Enable the strict flag in your tsconfig.json file.
Use keywords like never, unknown, and void cautiously for advanced scenarios.

Example:

{
  "compilerOptions": {
    "strict": true
  }
}

2. Avoid ‘any’ and Use Alternatives.

While coding, you should avoid using any as it turns off type-checking, which can lead to bugs and make the code more complex. The “any” type allows any value, directing to unexpected runtime errors, making the code harder to maintain and less predictable. Instead, you can utilize specific types for each variable, such as strings or numbers.

Additionally, using too much “any” can decrease the benefits of type-checking. Moreover, you can use union types when the variable can hold multiple types. As a result, it allows types without restoring ‘any’ in your coding process.

Essential Tips:

Use more specific types like string, number, or custom types whenever possible.
If you need flexibility, consider using interfaces or unions.

Example:

let data: any; // Not recommended
let data: unknown; // Better, requires type checking

function processValue(value: unknown) {
  if (typeof value === "string") {
    console.log(value.toUpperCase());
  }
}

3. Use Type Inference and Annotations

TypeScript provides a powerful type inference feature that allows developers to write cleaner and more concise code. Type inference lets TypeScript determine the type based on the assigned value, which can decrease redundancy in your code. However, explicit type annotations are crucial for maintaining clarity and readability, especially in complex or collaborative projects.

By explicitly annotating types for variables, parameters, and return values, you can make your code more understandable for team members who may be new to the codebase. This practice also helps catch potential errors early.

Essential Tips:

Utilize Type Interference when the case is simple and the type is clear.
Use Type annotations for complex projects, function parameters, and return types.

Example:

let name = "John"; // TypeScript infers type string
function greet(name: string): string {
  return `Hello, ${name}`;
}

Note: TypeScript infers the type of the variable `name` as `string`, and the function `greet` explicitly defines that it takes a `string` as an argument and returns a `string`. The function greet will accept a string and return one that says “Hello, .” Example: will return “Hello, John”.

4. Organize Code with Modules

Using modules can help you maintain a clean codebase for large, complex projects. TypeScript supports the ES6 module system, enabling you to break your code into smaller, reusable pieces. This practice improves scalability and makes the code more manageable.

Additionally, modules allow you to group related functions, variables, and classes into logical units. The organized code with modules enhances maintainability and makes it easier for different developers to work on various parts of the codebase.

Essential Tips:

Use the export and import keywords to define and use modules.

Example:

// utils.ts
export function add(a: number, b: number): number {
  return a + b;
}

// main.ts
import { add } from './utils';
console.log(add(2, 3));

5. Integration with Third-Party Tools

TypeScript seamlessly integrates with numerous third-party tools like Webpack and Babel, making it easier to merge into existing workflows. The tools can also help you set up a modern development environment.

By integrating these tools into your TypeScript projects, you can boost the development process and offer additional capabilities, such as code minification, module bundling, and compatibility with older browsers. Moreover, configuring these tools ensures your TypeScript project remains up-to-date and efficient with the latest development standards.

Essential Tips:

Execute DefinitelyTyped or package-provided type definitions for third-party libraries.
For a seamless development workflow, you can integrate TypeScript with build tools like Webpack, Rollup, or Babel.

Example:

// Install type definitions for a library
npm install --save-dev @types/lodash

// Use in your code
import _ from 'lodash';
let numbers = [1, 2, 3];
console.log(_.reverse(numbers));  // Output: [3, 2, 1]

6. Consistent Coding Style with ESLint and Prettier

The developer team must maintain a consistent coding style to ensure high readability and maintainability. With the help of tools like ESLint and Prettier, it becomes easier to maintain as it automates the process and ensures everyone stays on the same coding standards.

ESLint TypeScript best practices help identify potential and fix problems in your code, and Prettier automates formatting your code according to a consistent style. This practice is vital when multiple developers work on the same project and in collaborative environments.

Essential Tips:

Configure ESLint and Prettier in your project by installing the necessary packages and creating configuration files.

Example:

// .eslintrc.json
{
  "extends": ["eslint:recommended", "plugin:@typescript-eslint/recommended", "prettier"],
  "parser": "@typescript-eslint/parser",
  "plugins": ["@typescript-eslint"]
}

// .prettierrc
{
  "singleQuote": true,
  "trailingComma": "all"
}

7. Document Code for Scalability

Documenting your coding is crucial to maintaining and understanding the codebase, especially for complex and large projects. By utilizing JSDoc comments, you can document classes, functions, and modules within your TypeScript code.

A well-documented TypeScript code helps you to define parameters, types, and behavior functions. However, while documenting code, you must ensure the required changes to add new features and functionalities.

Essential Tips:

Ensure that your comments are descriptive and explain the return values of methods and functions.
Using tools like TypeDoc can generate documentation from your TypeScript comments.

Examples:

/**
 * Add two numbers together.
 * @param {number} a - The first number.
 * @param {number} b - The second number.
 * @returns {number} The sum of the two numbers.
 */
function add(a: number, b: number): number {
  return a + b;
}

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Advanced TypeScript Best Practices

1. Importance of Generics

Utilizing generics in TypeScript allows you to generate reusable, flexible, and functional components that can operate on multiple data types. Moreover, it supports writing type-safe code without hampering performance and coding activity.

For instance, a generic function can manage data types while maintaining type safety and identifying early errors. It is an advanced TypeScript best practice because it specifies unknown types and allows you to write versatile code efficiently.

Essential Tips:

Offer default values for generic parameters to make your code more flexible and user-friendly.
Employ constraints with generics to ensure that the generic types address particular structures or interfaces.

Example:

// Generic function with descriptive names and constraints
function mergeObjects(obj1: FirstType, obj2: SecondType): FirstType & SecondType {
  return { ...obj1, ...obj2 };
}

// Using the generic function
const person = { name: 'Alice' };
const job = { title: 'Developer' };

const employee = mergeObjects(person, job);
console.log(employee); // Output: { name: 'Alice', title: 'Developer' }

Note: Return Type is the function that returns an object that combines the properties of both FirstType and SecondType.

2. Union and Intersection Types

Implementing union and intersection types within your project can offer better flexibility and precision. The use of union types allows a variable to hold values of different types, for example, a number or string. It makes your functions more adaptable, and your parameters hold numerous types.

Meanwhile, intersection types enable your developers to combine multiple types into one within all properties of the constituent types, making them flexible. This TypeScript best practice is helpful for precise type definitions, merging different interfaces, and managing potential types.

Essential Tips:

Execute union types when a parameter or variable can be one of the several types used to enhance code adaptability.
Utilize Intersections types to combine multiple types into a single to ensure necessary properties.

Example:

// Union Type
let id: number | string;
id = 101; // valid
id = "A101"; // valid

// Intersection Type
interface Person {
  name: string;
}

interface Employee {
  employeeId: number;
}

type EmployeeDetails = Person & Employee;

const employee: EmployeeDetails = { name: 'Alice', employeeId: 123 };

3. Access Modifiers for Encapsulation

To secure your TypeScript classes, access modifiers for encapsulation is crucial. It helps to control the visibility of class methods and access the intended scope. As a result, these TypeScript best practices promote cleaner code with better encapsulation and eliminate the risk of unintended interactions.

In simple words, using “public”, “private”, and ” protected access modifiers”, you can control the accessibility and visibility of class members.

Essential Tips:

Mark methods or properties as private to restrict access within the class itself.
Only use protected for inheritance when you want access to the class and its subclasses, not for the outside members.

Example:

class Person {
  private name: string;

  constructor(name: string) {
    this.name = name;
  }

  getName(): string {
    return this.name;
  }
}

class Employee extends Person {
  protected employeeId: number;

  constructor(name: string, employeeId: number) {
    super(name);
    this.employeeId = employeeId;
  }

  getEmployeeId(): number {
    return this.employeeId;
  }
}

const emp = new Employee('Alice', 123);
console.log(emp.getName()); // valid, Output: Alice
console.log(emp.employeeId); // Error: Property 'employeeId' is protected and only accessible within class 'Employee' and its subclasses.

4. Utilize Enums for Readable Constants

Enums in TypeScript best practices allow you to define a set of named constants, which helps to make code more readable and maintainable. It can also make code less error-prone by replacing arbitrary values with relevant names for better clarity.

Moreover, it helps to manage related constants and can improve code clarity and integrity through defined enum members. Simply put, this practice represents a fixed set of associated values like options, states, and categories.

Essential Tips:

Need to define related constants with enums for better code readability and maintainability.
When the meaning of value is more vital than the numeric position, you can use string enums for clarity.

Example:

enum Direction {
  Up = 'UP',
  Down = 'DOWN',
  Left = 'LEFT',
  Right = 'RIGHT',
}

function move(direction: Direction) {
  console.log(`Moving ${direction}`);
}

move(Direction.Up); // Output: Moving UP

5. Error Handling

Effective error handling is one of the best practices in TypeScript for any robust application. To make it error-prone, you can utilize try-catch blocks to handle exceptions and ensure your app can handle issues without crashing gracefully.

Additionally, defining custom error types will help you categorize and define errors more efficiently. As a result, it improves user experience and aids in debugging the code.

Essential Tips:

Defining custom error classes for specific and clear error messages would be best.
Using try-catch for runtime errors will wrap code and eliminate unnecessary code errors.

Example:

class CustomError extends Error {
  constructor(message: string) {
    super(message);
    this.name = 'CustomError';
  }
}

function riskyOperation() {
  throw new CustomError('Something went wrong!');
}

try {
  riskyOperation();
} catch (error) {
  console.error(error.message); // Output: Something went wrong!
}

6. Readability Testing

Prioritizing code readability is crucial for maintaining the codebase. Adapting regular testing, such as end-to-end testing, integrated testing, and unit testing, will help you identify potential areas for improvement and ensure that the code is easy to understand by all team members.

Furthermore, this practice can ensure that your TypeScript code is manageable during collaborative environments. Even when the project grows, readability testing can help keep the code understandable and maintainable.

Essential Tips:

You must review code frequently to specify readability issues and ensure adherence to the coding standards.

Using linting tools like ESLint can help check automatically and implement the coding style as per the norms.

Example:

// Example of well-commented and formatted code
/**
 * Add two numbers together.
 * @param {number} a - The first number.
 * @param {number} b - The second number.
 * @returns {number} The sum of the two numbers.
 */
function add(a: number, b: number): number {
  return a + b;
}

Common Mistakes in TypeScript Best Practices: How to Avoid it?

TypeScript best practices are one of the most effective methods for enhancing code readability and efficiency. However, overlooking a few mistakes can create massive issues like minor errors. Here are the mistakes and how to fix it-

Mistakes	Solution
Overusing types ascertains	Utilize type assertions only when it is necessary and sparingly
Misusing “As” casts	Use “as” only when you are dealing with third-party libraries and complex type transformations
Skipping “unknown” over “any”	For type safety, use unknown than any
Poor project structure	Follow a consistent and clear project structure
Overloading functions improperly	Must ensure function overloads are implemented correctly and efficiently
Overcomplicating types	Define types and use type aliases and interfaces for accessible code
Inefficient use of TypeScript advanced features	Implement union types, mapped types, and intersections for robust code

Conclusion

Implementing TypeScript best practices 2024 can significantly improve your project codebase’s scalability, maintainability, quality, and flexibility. Prioritizing clean code principles, modern ES6+ features, and thorough documentation ensures seamless development and easier team collaboration.

By incorporating these best practices of TypeScript and utilizing the latest advancements, you can redefine your coding techniques, enhance your JavaScript development experience, and streamline the workflow of your TypeScript projects. For even more significant advancement, consider partnering with dedicated remote developers to ease your workflow further and achieve your project goals.

Frequently Asked Questions (FAQs)

What tools integrate well with TypeScript for development?

Tools that integrate well with TypeScript are the following:

ESLint: For linting and maintaining code quality.
Webpack: Module bundling.
Babel: transpiling TypeScript to JavaScript.
Prettier: code formatting.
Jest: for testing.

What are coding standards in TypeScript?

Coding standards in TypeScript are guidelines that set the uniform programming styles for writing source code. Several software companies follow the standard procedures to ensure well-defined, readable, and efficient code.